flyrotary@lancaironline.net Mailing List Archive

Steve,

Good suggestions. I have tried shutting off the secondary injectors with no noticeable change. I also checked to see if any of the secondary injectors were dribbling fuel. This did not show any leakage. Using an o-scope, I plan to look at the injector pulse width patterns in the near future. If there is something odd going on with the signal that ought to reveal it.

The throttle shaft for all three TB's is one-piece. It is a custom built piece made on a Bridgeport mill. So there is no adjustment from one TB to the next. Visual exam could not detect any mis-match in the butterflies.

Port timing is the same as these are peripheral port housings. These were also bored on a Bridgeport using the same SS tubing. Not sure how to test for exhaust runner backpressure. However, I have been running this same exhaust system prior to this problem. So, it does not seem to be high on the probability list.

Thanks,

Mark

On Mon, May 28, 2012 at 9:29 PM, Steven W. Boese <SBoese@uwyo.edu> wrote:

Mark,

It would seem to me that there are two possibilities: One is that rotor 1 is getting too much fuel at low to mid range or that rotor 1 is not getting as much air as the other rotors under these conditions.

To test the first possibility, one could disconnect the secondary injectors and observe the pulse width to the primary injectors to verify that they are the same. From the work you have done already, it seems unlikely that this would be the problem.

To test the second possibility, you could verify the synchronization of the throttle bodies, exchange the rotor 1 throttle body with one of the others, verify that the port timing of rotor 1 is the same as the others, and verify that the exhaust back pressures at the exhaust ports are consistent.

If the versatility of the EC2 allows you to compensate, the concern may be minimal, but there must be a reason for what is going on.

FWIW,

Steve Boese

RV6A, 1986 13B NA, RD1A , EC2

From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Mark Steitle [msteitle@gmail.com]
Sent: Monday, May 28, 2012 7:38 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Injector balancing

I'm in a bit of a dilemma and thought I would put this out here for the group to ponder.

First, this is a p-ported 3-rotor, running RWS EC-2 and psru. I'm running 460cc Mazda primary injectors and 60lb Deka IV secondary injectors. Primary injectors share a common fuel rail and are positioned close to the engine, between throttle plate and rotor face. Secondary injectors are located ahead of the throttle plates. As this is a p-port engine, it has three 1-bbl TB's, located very close to the engine. Engine will idle down to 800 - 900 rpm, but I normally idle it around 1500 - 1600 rpm.

The problem is this, the #1 rotor cuts out at low to mid-range RPM, evidenced by obvious reduced power, very low EGT's on rotor #1, change in exhaust tone, a dark residue in the #1 exhaust port and dark spark plugs on #1. Just today I was able to get it to run normally with balanced EGT's by adjusting Mode 4, but I had to go full CCW with the program knob to achieve this. (Mode 4 & 5 adjust similar to Mode 1) Now it runs well mid-range and the dropped #1 rotor is happily firing away. I still have some tuning to do, but after adjusting Mode 4, I can now move forward with that.

To date I have tried the following:

1. Performed a compression check - OK

2. Swapped primary injector with #3 - no change

3. Swapped coils with #3 - no change

4. Replaced spark plugs - no change, except initially it ran better until the plug fouled

5. Checked plug wires with ohm meter - checked good

6. Sent EC-2 to Tracy for latest s/w and checkout - no abnormalities found, latest s/w installed

7. Checked secondary injectors for leakage - none seen

Can anyone suggest a reason why the #1 primary injector runs extremely rich when set to the factory default setting? Is this something to be concerned with?

Thanks,

Mark